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Old 06-06-2010, 10:52   #1
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Uninsulated (?!) Backstay as SSB Antenna ?

This thread over on SSCA:

SSCA Discussion Board • View topic - HF Dipole Question


Seems to say that an uninsulated backstay (or mast) can be used for an SSB antenna.

This piqued my interest, to say the least, as the only thing preventing me from installing an SSB radio is the ugly prospect of cutting my backstay.

Ugly for me because:

1. Isolaters for my jumbo 16mm backstay are prohibitively expensive; and

2. I just don't want to cut up such a structurally crucial part of the boat.

Any comments? I tried to register on SSCA to ask the question there, but the confirmation code system in the registration process is so poorly implemented that the code is utterly illegible, and there is no way for unregistered people to contact the administrator. So I am permanently locked out there.
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Old 06-06-2010, 11:37   #2
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Didn't read through the linked thread but I am sure it someplace must make the distinction between an un-insulated backstay vs. a grounded backstay, the latter being a problem with RF. If the backstay is grounded, it may still work but at the expense of other problems. If it's not grounded, the only issue becomes what other parts are interconnected and whether or not it/they will be effected by RF. Every boat is different.
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Old 06-06-2010, 12:01   #3
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Originally Posted by S/V Illusion View Post
Didn't read through the linked thread but I am sure it someplace must make the distinction between an un-insulated backstay vs. a grounded backstay, the latter being a problem with RF. If the backstay is grounded, it may still work but at the expense of other problems. If it's not grounded, the only issue becomes what other parts are interconnected and whether or not it/they will be effected by RF. Every boat is different.
Indeed. They say that the backstay becomes a "grounded multipole vertical".

All Greek to me, but if there is sme way to avoid cutting my poor backstay, I'm all ears.
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Old 06-06-2010, 12:27   #4
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"grounded multipole vertical" sounds like an acronym for connecting the antenna directly to ground - analogous to using your cold water pile at home as an antenna.
I have never seen a propely installed insulated backstay fail but I can relate to the idea of having one less thing to worry about or add to the maintenance list by eliminating it/them.

I'd still go for the standard fliberglass 23 ft whip antenna if you want a multi-freq antenna.
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Old 06-06-2010, 12:39   #5
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A freinds boat simply used an insullated copper wire attached with clips to the backstay.The wire ran most of the way up the backstay.
He reported good SSB performance.
This set up is obviously not ideal, but it seems to work in practice at least in this case. No insulators needed.
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Old 06-06-2010, 13:34   #6
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I have since '86 used an uninsulated and grounded backstay as my sole antenna on Feeling Good. I've used it with a manual tuner feeding it via low loss coax (9913) from the chart table. I am currently using a SGC-230 automatic tuner located in the aft cabin to feed it via GTO-15 wire. In both setups the feed point is located about 8 feet above the deck to provide a good match. This antenna has performed exceptionally well on the HF ham bands and SSB frequencies. This included daily check-ins on the Pacific Seafarer's Net and emergency operations with the USGC.

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Old 06-06-2010, 14:51   #7
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A grounded backstay is a perfectly valid configuration, and grounded vertical antennas are often used in land-based installations. The trick is the matching network, and I don't know how well the typical antenna tuner will perform over the full range of the marine bands. It's easy enough to find the proper connection point and build a matching network for a specific frequency, but it might be tough to make it work well over the full range.

I'm not saying it can't be done, or that the standard ATUs couldn't do the job -- I just don't know. In theory though, there's nothing wrong with the grounded vertical/backstay.
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Old 06-06-2010, 15:14   #8
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You don't have to go to a grounded backstay in order to have a good SSB antenna, without cutting the backstay.

Dockhead...I agree with you: no sense cutting up a perfectly good backstay -- 16mm or not -- and putting in six new potential points of failure!

A solution which works well for many people is an "alternate backstay", made of s/s lifeline. It can be of almost any length over 23' (around 40' is good for many installations), and is fed with GTO-15 wire thru the deck to a tuner located close underdeck. You hoist one end with a spare halyard, and tie off the lower end on the forward end of the pushpit. Either port or starboard....whichever is convenient.

I've had one on my boat for over 20 years. And, I do this for a living....have installed many of them. They work just as well as insulated backstays, and are very robust. They can stand up to hurricane-force winds (mine went thru 5 over-100 knot hurricanes in the BVI). Here's a pic of the lower end of mine:
DSC_0028

There have been extensive discussions about this solution on this Board, SailNet, and SSCA's board.

Bill

BTW, with modern tuners you can tune up to DC-grounded things, including your rigging or your bedsprings. That says nothing about how much power loss is involved, and how good a signal will be radiated :-)

B.
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Old 06-06-2010, 16:01   #9
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G'Day Dockhead,

Well, at the risk of being flamed for various transgressions, I must report that on both Insatiables (I and II) I have simply fed the rigging from a MFJ manual tuner. On I-one it was convenient to feed the bottom of the backstay, and now on I-two I feed the chainplate for the port shrouds. In both cases I have had no trouble matching the impedances on frequencies from 80 metres up through 10 (3.5 to 30 MHz). Neither installation did well on the 2 MHz band, so I was unable to use 2182 KHz which might bother some folks. In both cases I have tried it with the base of the mast grounded to the keel, and with it isolated. It changed the settings on the tuner, but didn't seem to affect the signal strength as reported by distant stations.

At any rate, the radiated signals were always comparable to those from nearby boats with insulated backstay antennas. I once had the experience of talking from the Society Islands to a ham in England on 20 metres... he claimed that such an antenna couldn't possibly work. PErhaps he hadn't noticed that it was working!

I wouldn't be brave enough to tell you that it will work for your boat, but it surely did for mine.

Cheers and good luck.

Jim (N9GFT/VK4GFT) and Ann s/v Insatiable II lying Port Stephens, NSW, Oz enjoying some really crappy wx.
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Old 06-06-2010, 17:35   #10
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Jim,

No flame. You just illustrate my point: DC-grounded antennas can work. After all, most VHF antennas are DC-grounded. And, with care and a bit of skill, you can tune up into almost anything. Sometimes it works pretty well, sometimes it doesn't. If you're a ham, and you have the skill and interest, by all means experiment. But if you're the typical boat owner who just wants/needs a good SSB installation, why not go with tried and proven methods which will bring home the bacon?

I once worked from the BVI into New Zealand with a FT-817 running 2.5 watts! Got a 59 report, too. And I once worked trans-Atlantic from Morocco, using an 8' aluminum curtain rod as an antenna. First call got a 59 report from Iowa. So what?

When it comes to SSB installations on boats, my experience tells me you need to do the very best you can to organize something which will be good day-in and day-out, in good propagation conditions and in poor. You want to optimize your setup to provide the very best communications you can, within reason.

Listen regularly to any maritime net. There are boats which almost always have good signals, and there are boats which almost always have poor signals. The difference is in the quality of their installations, not in their radios. And, more often than not, the differences are dramatic.

BTW, Jim, I notice that you and I have the same birth year....so, I guess, we've both been round the block a few times :-)

Cheers and 73's,

Bill
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Old 06-06-2010, 17:46   #11
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What about rigging a dipole that can be hoisted or mounted on the standing rigging? Read a couple of articles, most notably an article on the website atomvoyages Atom Voyages | Making a Dipole Antenna

So assuming correct installation which antennae will give the best, most reliable communication: insulated backstay, not insulated backstay, dipole, whip?

Thanks
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Old 06-06-2010, 18:10   #12
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Skip,

It depends. Nothing, but nothing will beat a single-band, tuned vertical dipole for long-distance communications. However, the limitations of most cruising boats restrict this type of antenna to overall lengths of 40-50' or less, meaning that for practical purposes you can't really mount a half-wave vertical dipole for bands below about 10mHz. A 20m or 15m dipole for the ham bands works great. But, you're restricted to those bands.

For general, all-band performance an insulated end-fed backstay-like antenna about 40-50' long is about the best you can do on a sailboat. These require a tuner at their base, and are quite versatile. They can tune all marine and ham bands, and put in a pretty good, if not exceptional performance. IMHO, every boat ought to have such an antenna.

We've recently had pretty good luck with using an UN-UN (unbalanced-to-unbalanced transformer...similar to a balun) and a 50' length of wire. The UN-UN allows you to run coax from near the base of the antenna forward to a tuner located near the radio, or an internal tuner in the radio. Lower band performance has been quite good, and the antenna performs quite well on the higher bands as well. VK2JBZ, Ross, has been experimenting with this setup for months on his 47' sloop.

Vertical antennas (whips, screwdriver, etc.) can do pretty well on some bands. The best of these do quite well, but they're large and unwieldy on smaller yachts.

Here's a summary of options for a sailboat: MarineAntennaChoices2

Bill
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Old 06-06-2010, 19:35   #13
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Hi Bill,

Thanks for the link. Except for the band limitations the dipole looks interesting. Even better, you don't need a tuner.
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Old 05-07-2010, 23:08   #14
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Another option for antenna installation

Hi all,

I have another option for possible antenna installation on a boat and as far as I am using it very successfully I will share information with you.
I wanted to remove the majority of the energy emitted from the cockpit area etc and did not find sufficient arguments to do the insulated backstay (considering the increased chances to fail), either. Thus I top feed the antenna grounded on mast itself! Works great! I used several other options before, either they did not look nice or they were not practical.

Several years ago when I was changing all the cables in the mast I have put additional spare coaxial cable up the mast. Then I connected the connector with the hot part of the antenna (wire going separately down) and put ground on the mast itself. The antenna works great (length was 43ft of wire) - NO BALUN - just center isolator and that's it! Check for my dxcluster signal reports and you will see I rock on the bands with ic7000 + AT7000 tuner usually running about 50W and this antenna setup.
This setup works fine, however just today (that is why I am looking information on the internet) I will try to improve it by adding UN-UN balun 4:1 to remove the radiation from the coax and make this system even more efficient (on a top mast) (I had problems on low bands with RF; the additional weight on a top of the mast is not that big that would alter the sailboat performance or effect its stability.......

If you wanna see my marine setup check my page at www.qsl.net/s51ta

If there will be interest I can post add. info .....

All the best,
Ted Mezek, s51ta
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Old 06-07-2010, 04:06   #15
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Quote:
Originally Posted by btrayfors View Post
Skip,

It depends. Nothing, but nothing will beat a single-band, tuned vertical dipole for long-distance communications. However, the limitations of most cruising boats restrict this type of antenna to overall lengths of 40-50' or less, meaning that for practical purposes you can't really mount a half-wave vertical dipole for bands below about 10mHz. A 20m or 15m dipole for the ham bands works great. But, you're restricted to those bands.

For general, all-band performance an insulated end-fed backstay-like antenna about 40-50' long is about the best you can do on a sailboat. These require a tuner at their base, and are quite versatile. They can tune all marine and ham bands, and put in a pretty good, if not exceptional performance. IMHO, every boat ought to have such an antenna.

We've recently had pretty good luck with using an UN-UN (unbalanced-to-unbalanced transformer...similar to a balun) and a 50' length of wire. The UN-UN allows you to run coax from near the base of the antenna forward to a tuner located near the radio, or an internal tuner in the radio. Lower band performance has been quite good, and the antenna performs quite well on the higher bands as well. VK2JBZ, Ross, has been experimenting with this setup for months on his 47' sloop.

Vertical antennas (whips, screwdriver, etc.) can do pretty well on some bands. The best of these do quite well, but they're large and unwieldy on smaller yachts.

Here's a summary of options for a sailboat: MarineAntennaChoices2

Bill
Thanks everyone, and especially Bill, for all the thoughtful input. I'm still pretty puzzled, however.

The fundamental problem is that I want to use such a highly technical device as an SSB radio without diving too deeply into all this delightfully wonky stuff. If I had a lot of time on my hands I would love it, but I am not retired and don't. I've got my hands more than full with all of the other delightfully wonky equipment on board (read: toys for grownups). Ham radio has always seemed to be wonkiness for its own sake; technical mastery of an arcane art with quite little and dwindling application in real life, especially since the Internet and Skype and other means of instant gratification world-wide communication. Nothing at all wrong with that; on the contrary, I could be very interested in such a thing if I had enough time on my hands. But I don't so I would like to keep this relatively straightforward.

So what to do? It seems like it comes down to three more or less realistic choices, based on all this good advice:

1. Bite the bullet, do the usual conventional thing, insulate my backstay and rig it to an automatic tuner.

2. Do the unconventional thing and try the use the backstay without insulating it.

3. Rig a wire in parallel to the backstay or a shroud and use it as a quasi-insulated backstay.

Variant 1 is $$$$ and worries me structurally. But it is elegant in that I don't add more wires aloft, there's nothing to get blown down, snagged, etc., and I can be pretty sure that it will work pretty well.

Variant 2 would be pretty much ideal if it works. Cheap, simple, elegant, seaworthy.

Variant 3 adds more crap aloft to snag, get blown down, create windage, look ugly, etc., although if it runs up a shroud instead of the backstay maybe these disadvantages are reduced. My masthead is 75 feet above the water, so a shroud should be plenty long enough. Will also simplify the cable run to the radio.

What do you all think?
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